1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
#include <bits/stdc++.h>

const int MAX_N = 300;
int n, m, k;
std::vector<int> list[MAX_N+3];
int res;

void input(){
    std::cin >> n >> m >> k;
    int a, b;
    for (int i = 1; i <= m; i++){
        std::cin >> a >> b;
        list[a-1].push_back(b-1);
    }
}

int dp[MAX_N+3];

int getRes(std::vector<int> &t){
    for (int i = 0; i < n; i++)
        dp[i] = 1;
    for (int i = 0; i < n; i++)
        if (t[i])
            dp[i] = 0;
    for (int i = n-1; i >= 0; i--){
        if (t[i])
            continue;
        for (auto u: list[i])
            if (!t[u])
                dp[i] = std::max(dp[i], dp[u] + 1);
        if (dp[i] >= res)
            return dp[i];
    }
    int res = 0;
    for (int i = 0; i < n; i++)
        res = std::max(res, dp[i]);
    return res;
}

int main(){
    std::ios_base::sync_with_stdio(0); std::cin.tie(NULL);
    input();

    std::vector<int> t;
    for (int i = 1; i <= n-k; i++)
        t.push_back(0);
    for (int i = 1; i <= k; i++)
        t.push_back(1);
    res = INT_MAX;
    do{
        res = std::min(res, getRes(t));
    } while (std::next_permutation(t.begin(), t.end()));
    std::cout << res << "\n";
}